Ion implantation system with mixture of arc chamber materials

ABSTRACT

A system and method for ion implantation is described, which includes a gas or gas mixture including at least one ionizable gas used to generate ionic species and an arc chamber that includes two or more different arc chamber materials. Using the system ionic species are generated in the arc chamber with liner combination, and one or more desired ionic species display a higher beam current among the ionic species generated, which is facilitated by use of the different materials. In turn improved implantation of the desired ionic species into a substrate can be achieved. Further, the system can minimize formation of metal deposits during system operation, thereby extending source life and promoting improved system performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 62/875,869 filed Jul. 18, 2019 and which is incorporatedby reference herein.

FIELD

The present disclosure relates to an ion implantation system having anarc chamber that uses a mixture of two or more different materials, andmethods for ion implantation using the system.

BACKGROUND

Ion implantation involves deposition of a chemical species into asubstrate, such as a microelectronic device wafer, by impingement ofenergetic ions of such species on the substrate. In order to generatethe ionic implantation species, the gas, which may for example comprisea halide or hydride species, is subjected to ionization. This ionizationis carried out using an ion source to generate an ion beam. The ionsource is typically a gas or gas mixture.

Once generated at the ion source, the ion beam is processed byextraction, magnetic filtering, acceleration/deceleration, analyzermagnet processing, collimation, scanning and magnetic correction toproduce the final ion beam that is impinged on the substrate.

Upon ionization, an ionizable gas typically generates multiple ionicspecies. Each ionic species derived from a starting compound (e.g., gas)has a different atomic composition than another ionic species, and theremay be a desire to implant certain species, a desire to avoid implantingcertain species, or both, based on these atomic composition and desiredmodification of the substrate. However, upon ionization and underconditions used to generate the ion beam for implantation, each ionicspecies have a beam current which can affect implantation of speciesinto the substrate.

Ion implantation processes can also become increasingly complex whenadditional ionic species are generated in the arc chamber by thereaction of gas species with chamber material, such as the reaction offluoride ions with tungsten arc chamber to generate tungsten fluorides.

Various challenges remain for improving ion beam performanceparticularly as ion implantation processes become more complex.

SUMMARY

This disclosure relates to systems and methods for implanting ionicspecies into a substrate in an ion implantation process. In manyaspects, the disclosure provides ways to alter or improve performance ofthe ionic species generated from a gas or gas mixture by selecting andusing mixtures of different arc chamber materials together with a one ormore ionizable gases. The system includes an arc chamber with two ormore different arc chamber materials. The presence of the second,different, arc chamber material that is different than the first arcchamber material facilitates increased beam current performance for oneor more desired ionic species upon ionization of the ionizable gas. Thisallows improved implantation of the one or more desired ionic speciesinto the substrate using its higher beam current. It can also minimizedeposition of ionic species that are not desirably introduced in thesubstrate, as those species will have lower beam currents

The mixture of different materials used for construction of portions ofthe arc chamber can also minimize formation of unwanted arc chamberdeposits that otherwise form during system operation, such as resultingfrom reaction of gases (e.g., fluoride gasses) with chamber materials(e.g., tungsten). As such, unwanted deposits caused by reaction of arcchamber material can be minimized thereby extending source life andpromoting improved system performance.

In one aspect, the disclosure provides a system for implanting an ionicspecies into a substrate, with the system including a gas sourcecomprising a gas or gas mixture capable of forming at least one ionicspecies when ionized. The system includes an arc chamber comprising twoor more different arc chamber materials wherein a first arc chambermaterial is different than a second chamber material. The arc chamberincludes arc chamber walls having interior-plasma facing surfaces, andoptionally one or more arc chamber liners configured to contact all or aportion of the interior-plasma facing surfaces.

In some aspects, the two of more different arc chamber materials includefirst and second arc chamber materials having one or more atomsincluding but not limited to tungsten, molybdenum, carbon, silicon,boron, magnesium, calcium, aluminum, fluorine, indium, nitrogen, oxygen,gallium, germanium, and lanthanum. The first and second arc chambermaterials can include individual compounds, intermetallics, alloys,composites, solid solution (an alloy formed by a matrix “solvent” metalwith another “solute” element atomically dispersed in its crystalstructure with solute to solvent ration being continuous over a smallrange), and mixtures of solid materials. In some embodiments, the firstor second arc chamber materials can include a graphite-containingmaterial, a carbon-containing material, a boron-containing, agermanium-containing, an antimony-containing, a tungsten-containing, amolybdenum-containing a fluorine-containing, a nitrogen-containing, anoxygen-containing material, a ceramic material, or an alloy. Forexample, the first or second arc chamber material can include graphite(C), boron (B), germanium (Ge), boron nitride (BN), (boron oxide) B₂O₃,(germanium oxide) GeO₂, silicon carbide (Sick), tungsten carbide (WC,W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃),tungsten germanium W₂Ge₃, calcium carbide (CaC₂), Al₄C₃, (magnesiumcarbide) Mg₂C, (aluminum fluoride) AlF₃, (gallium fluoride) GaF₃,(indium fluoride) InF₃, (gallium nitride) GaN, aluminum nitride (AlN),(indium nitride) InN, tungsten lanthanum oxide (WLa₂O₃), gallium oxide(Ga₂O₃), (indium oxide) In₂O₃, antimony oxide (Sb₂O₃), or aluminum oxide(Al₂O₃). The first or second arc chamber material can also include atungsten alloy. An exemplary tungsten-based alloy is WB_(2-x),x=0.001-0.5.

In one exemplary embodiment, a first arc chamber material is tungstenand a second arc chamber material includes carbon in the form ofgraphite or a carbide compound.

In another exemplary embodiment, a first arc chamber material istungsten and a second arc chamber material include a boron-containingmaterial in the form of elemental boron, a boride compound or aboron-containing alloy.

Yet, in another exemplary embodiment, a first arc chamber material or asecond arc chamber material is selected from isotopically enrichedmaterials in one or more isotopes relative to their natural abundance.In one exemplary embodiment, a first or second arc chamber material is aboron-containing material with isotopically enriched boron in B-11isotope. In another exemplary embodiment, a first or second arc chambermaterial is a germanium-containing material enriched in one or moregermanium isotopes such as Ge-72 isotope.

These different arc chamber materials can be present in the arc chamberin various arrangements. The first or second arc chamber materials canbe present in all or a portion of one or more of arc chamber liner(s) orarc chamber piece(s). In one type of arrangement, the second arc chambermaterial is coated onto or surface graded into, a portion of or all ofthe arc chamber walls with the arc chamber walls being made of the firstarc chamber material. In another arrangement, the arc chamber has one ormore arc chamber liners, with the one or more arc chamber linersincluding at least one of the first or second arc chamber materials. Instill yet another embodiment, the first or second arc chamber materialmay be provided as separate piece or target that is disposed in the arcchamber.

In another aspect, the disclosure provides a method for implanting oneor more ion species into a substrate. The method includes providing asystem as described herein having a gas source comprising a gas or gasmixture capable of generating at least one ion species when ionized, anarc chamber having at least first and second arc chamber materials thatare different. In the method a substrate is present in an implantationchamber and the system is operated to implant the one or more ionspecies into the substrate. Exemplary ionizable gases include, but arenot limited to silicon containing gases, boron containing gases,germanium containing gases, carbon containing gases, phosphoruscontaining gases, arsenic containing gases, antimony containing gases,tungsten containing gases, nitrogen containing gases, gallium containinggases, indium containing gases, tin containing gases, and aluminumcontaining gases. The ionizable gas can be co-flowed or provided inmixture with at least one other gas. The at least one other gas caninclude a co-gas which contains the same species as the ionizable gas,and/or a diluent or carrier gas.

In the method, a gas or gas mixture capable of generating ionic speciescan be flowed into the arc chamber at a predetermined flow rate. Uponapplication of a predetermined power and voltage in the arc chamber,ionic species can be generated from the gas or gas mixture, with thespecies including one or more desired ionic species for substrateimplantation. Using desired operating conditions of the system, the beamcurrent ionic species is increased to a greater extent than any of theother ionic species due to the presence of the second arc chambermaterial, relative to the beam currents of the ionic species generatedwithout the second arc chamber material under the same operatingconditions. Using this method, the ionic species with the greatest beamcurrent can be selected for implantation into the substrate.

In an exemplary mode of practice, the ionizable gas or gas mixture isflowed into the arc chamber at a predetermined flow rate. Exemplarygases can include CO, CO₂, CF₄, CH₄, C_(x)H_(y)F_(z), BF₃, B₂F₄, B₂H₆,PH₃, PF₃, PF₅, AsH₃, AsF₃, AsF₅, GeF₄, GeH₄, Ge₂H₆, SiF₄, Si₂F₆, SiH₅,S₁₂H₆, Si₃H₈, SbH₃, SbF₅. In some embodiments, the gas or gas mixturecan include an isotopically enriched gas such as, for example,isotopically enriched BF₃ gas or isotopically enriched GeF₄ gas, but notlimited to these. In some embodiment, the ionizable gas is a boroncontaining gas mixture including BF₃ and at least one additional gas.The at least one additional gas can include a co-species gas (e.g. B₂F₄,B₂H₆) and/or a diluent gas (e.g. H₂, Xe, Xe/H₂, Na, Kr, Ar, He).Specific examples of gas mixtures can include: BF₃/H₂; BF₃/B₂F₄;BF₃/B₂F₄/H₂; BF₃/B₂H₆; BF₃/B₂H₆/H₂; BF₃/Xe+H₂; and BF₃/B₂H₆/Xe+H₂, butnot limited to these. The BF₃ gas can be enriched BF₃ gas.

Upon application of a predetermined power and voltage in the arcchamber, one or more ions and one or more ionic species ionic speciescan be generated from the ionizable gas or gas mixture. Exemplary ionicspecies include ions such as a C⁺ ion, a B⁺ ion, a N⁺ ion, a F⁺ ion, aSi⁺ ion, an Ge⁺ ion, a P⁺ ion, an As⁺ ion, a Ga⁺ ion, a Sb⁺ ion, a In⁺ion, a Al⁺ ion, a Sn⁺, etc. Multi-atom ionic species can also begenerated such as CF₃+, CF₂+, CF+, BF+, BF₂ ⁺, SiF₃ ⁺, Si₂+, SiF+,GeF₃+, GeF₂₊.

In the arc chamber having two different arc chamber liner materials, theionic species each have beam currents generated using the desiredoperating conditions, with a desired ionic species having an optimizedbeam current, as measured against the ionic species beam currentsgenerated using the same optimal operating conditions but without thesecond arc chamber material. That is, the desired ionic species displaysa significant increase in beam current using the mixture of differentarc chamber materials as compared to an arc chamber being composed ofonly one material, where other, non-desired ionic species (e.g., thosehaving non-metal ions or metalloid ions), either do not display anysignificant increase in current, have the same current, or have areduced beam current using the liner mixture as compared to the singleliner. In turn, the higher beam current for the desired ionic speciesfacilitates its improved implantation into the substrate, while theimplantation of other non-desired ionic species can be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an ion implantation system,including an arc chamber with a gas feed line for feeding dopant sourcegas to the arc chamber for ionization thereof in the chamber.

FIG. 2 is a cross section of the FIG. 1 ion implantation systemschematically showing the generation of a plasma in the arc chamber ofsuch system.

FIG. 3 is a perspective view, in cross-section, of an ion sourceassembly comprising an ion source apparatus.

FIG. 4 is a schematic representation of an ion implant process systemincluding a storage and dispensing vessel containing gas which issupplied for ion implantation doping of a substrate in the illustratedion implant chamber.

FIG. 5 is a top-down view of an ion source chamber as described,containing different liners.

FIG. 6 is a top-down view of an ion source chamber as described,containing different liners.

FIG. 7A is a top-down view of an ion source chamber as described,containing different liners. The first side liner, the second side linerand the bottom liner are in one piece.

FIG. 7B is a side cross section view of an ion source chamber asdescribed, containing different liners. The first side liner, the secondside liner and the bottom liner are in one piece.

FIG. 8 shows F⁺ beam current data from experiments using a CF₄ gas inthe presence of a mixed tungsten/graphite liner, which produced a higherr beam at lower gas flow rates, versus graphite and tungsten liners.

FIG. 9 shows ionized species from experiments using CF₄ gas, with ahigher r beam, using a mixed tungsten/graphite liner versus graphite andtungsten liners, and lower W⁺ and WF_(x) ⁺ beams when using versus atungsten liner.

DETAILED DESCRIPTION

Embodiments of the disclosure relate to systems and methods for ionimplantation, wherein the system includes an arc chamber used for ionimplantation and having at least two different arc chamber materials.Any type of ion implantation system can be used for the ion implantationmethods as described herein. The arc chamber has arc chamber walls withinterior-plasma facing surfaces. Optionally there are one or more arcchamber liners configured to contact all or a portion of theinterior-plasma facing surfaces of the walls of the arc chamber. In thearc chamber the two or more different arc chamber materials are presentin the arc chamber walls, in one or more optional arc chamber liners, orboth. The system also includes a gas source that provides a gas or gasmixture capable of forming at least one ion species when ionized.Further, the system can include an implantation chamber in which the oneor more ionic species, which generated in the arc chamber, can beimplanted into a substrate.

The system with two different arc chamber materials can be used forproviding improved ion implantation, and in various aspects used formethods in which an ion-generating gas or gas mixture generates aplurality of ionic species. The system can be operated with apredetermined flow rate of the ion-generating gas or gas mixture, apredetermined arc power, and predetermined source magnetic field. Theoperating conditions can provide an optimized beam current for a desiredion species among the plurality of ionic species, which in turn can betargeted for implantation into a substrate.

In some arrangements, the arc chamber has walls with interior-plasmafacing surfaces (i.e., those surfaces of the arc chamber that contactplasma when the system is in use). The interior facing surfaces can bepresented by a first sidewall, a second sidewall, a cathode sidewall, ananti-cathode sidewall, a bottom, and a top of the arc chamber. All or aportion of the interior-plasma facing surfaces of the first sidewall,second sidewall, cathode sidewall, anti-cathode sidewall, bottom, and/ortop can include the second, different, arc chamber material in the formof a coating, surface grading, or arc chamber liner. The interior-plasmafacing surfaces of the arc chamber can present a total interior-plasmafacing surface area, and the amount of arc chamber materials can bedefined in terms of a percent amount of materials of the totalinterior-plasma facing surface area. For example, the system can includeat least a portion of the arc chamber liner formed of the second arcchamber material, wherein the arc chamber liner covers a certainpercentage of the total interior-plasma facing surface area of thechamber. As another example, the system can include at least a portionof one or more of the interior-plasma facing surfaces of the one arcchamber walls surface graded or coated with the second arc chambermaterial, with a desired percentage of the total interior-plasma facingsurface area coated or surface graded with the second arc chambermaterial.

The arc chamber includes two of more different arc chamber materials.These different arc chamber materials can be present in the arc chamberin various arrangements. The first or second arc chamber materials canbe present in all or a portion of one or more of arc chamber liner(s) orarc chamber piece(s). In one embodiment, the second arc chamber materialis coated onto or surface graded into, a portion of or all of the arcchamber walls with the arc chamber walls being made of the first arcchamber material. In another embodiment, the arc chamber has one or morearc chamber liners, with the one or more arc chamber liners includingthe second arc chamber material. A liner may be a flat, e.g., planarpiece of structure having two opposed major surfaces and a thicknesstherebetween. A liner may be rectangular, curved (e.g., rounded),angular, or otherwise shaped. A liner can be removable, meaning that theliner can be inserted and removed from the interior space of the ionsource chamber. In other cases, a liner can be permanent andnon-removable from the chamber. In still other embodiments, the first orsecond arc chamber material can be provided as a separate piece ortarget that is mounted in the arc chamber or received in a recess formedin the liner or the arc chamber walls for this purpose. The separatepiece may be of any suitable shape or size such that it can be disposedin the arc chamber. In one embodiment, the separate piece includes thesecond arc chamber material and the arc chamber walls and/or linerincludes the first arc chamber material, the first and second arcchamber materials being different from one another. In embodiments, theseparate piece is a consumable structure and reacts with the ionizablegas or gas mixture. In one example, the separate piece is a sputteringtarget.

In exemplary embodiments, one of the at least two different first andsecond arc chamber materials can be any one or more of the followingmaterials: graphite (C), boron (B), germanium (Ge), boron nitride (BN),boron oxide (B₂O₃), germanium oxide (GeO₂), silicon carbide (SiC),tungsten carbide (WC, W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boroncarbide (B₄C, B₁₂C₃), tungsten germanium (W₂Ge₃), calcium carbide(CaC₂), aluminum carbide (Al₄C₃), magnesium carbide (Mg₂C), aluminumfluoride (AlF₃), gallium fluoride (GaF₃), indium fluoride (InF₃), boronnitride (BN), gallium nitride (GaN), aluminum nitride (AlN), indiumnitride (InN), tungsten lanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃),indium oxide (In₂O₃), antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃).In some cases the arc chamber includes three or more different arcchamber materials with at least two arc chamber materials, which aredifferent, selected from graphite (C), boron (B), germanium (Ge), boronnitride (BN), boron oxide (B₂O₃), germanium oxide (GeO₂), siliconcarbide (SiC), tungsten carbide (WC, W₂C), tungsten boride (WB, W₂B,WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungsten germanium (W₂Ge₃),calcium carbide (CaC₂), aluminum carbide (Al₄C₃), magnesium carbide(Mg₂C), aluminum fluoride (AlF₃), gallium fluoride(GaF₃), indiumfluoride (InF₃), boron nitride (BN), gallium nitride (GaN), aluminumnitride (AlN), indium nitride (InN), tungsten lanthanum oxide (WLa₂O₃),gallium oxide (Ga₂O₃), indium oxide (In₂O₃), antimony oxide (Sb₂O₃) oraluminum oxide (Al₂O₃). In some cases the arc chamber includes four ormore different arc chamber materials with at least three arc chambermaterials, which are different, selected from graphite (C), boron (B),germanium (Ge), boron nitride (BN), boron oxide (B₂O₃), germanium oxide(GeO₂), silicon carbide (SiC), tungsten carbide (WC, W₂C), tungstenboride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungstengermanium (W₂Ge₃), calcium carbide (CaC₂), aluminum carbide (Al₄C₃),magnesium carbide (Mg₂C), aluminum fluoride (AlF₃), galliumfluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN), galliumnitride (GaN), aluminum nitride (AlN), indium nitride (InN), tungstenlanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide (In₂O₃),antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃. In some cases the arcchamber includes five or more different arc chamber materials with atleast four arc chamber materials, which are different, selected fromgraphite (C), boron (B), germanium (Ge), boron nitride (BN), boron oxide(B₂O₃), germanium oxide (GeO₂), silicon carbide (SiC), tungsten carbide(WC, W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C,B₁₂C₃), tungsten germanium (W₂Ge₃), calcium carbide (CaC₂), aluminumcarbide (Al₄C₃), magnesium carbide (Mg₂C), aluminum fluoride (AlF₃),gallium fluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN),gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN),tungsten lanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide(In₂O₃), antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃).

In some embodiments, at least one of the first, second, third, fourth,etc., arc chamber material can be a selected from isotopically enrichedmaterials in one or more isotopes relative to their natural abundance.In one exemplary embodiment, a first or second arc chamber material is aboron-containing material with isotopically enriched boron in B-11isotope. In another exemplary embodiment, a first or second arc chambermaterial is a germanium-containing material enriched in one or moregermanium isotopes such as Ge-72 isotope.

The resulting mixture of two or more different arc chamber materials canimprove the ion implant performance, including beam current and sourcelife for a gas or gas mixture including one or more ions for ionimplantation. In some embodiments, the presence of the two or moredifferent arc chamber materials can reduce the amount of tungstenfluoride formed during an implantation process.

In some arrangements, the system of the disclosure can include two ormore arc chamber liners with a first arc chamber liner made fromtungsten, or tungsten and a combination of one or more materials, and asecond arc chamber liner made from a material or combination ofmaterials different than the first arc chamber liner. The arc chamberliner can be a flat, e.g., planar piece of structure having two opposedmajor surfaces and a thickness therebetween. A liner may be rectangular,curved (e.g., rounded, U-shaped), angular, or otherwise shaped. A linercan be removable, meaning that the liner can be inserted and removedfrom the interior space of the ion source chamber. In other cases, aliner can be permanent and non-removable from the chamber. Inembodiments, the arc chamber includes two or more insertable liners,with one of the insertable liners formed from tungsten, and the arcchamber liner formed from a material such as graphite (C), boron (B),germanium (Ge), boron nitride (BN), boron oxide (B₂O₃), germanium oxide(GeO₂), silicon carbide (SiC), tungsten carbide (WC, W₂C), tungstenboride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungstengermanium (W₂Ge₃), calcium carbide (CaC₂), aluminum carbide (Al₄C₃),magnesium carbide (Mg₂C), aluminum fluoride (AlF₃), galliumfluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN), galliumnitride (GaN), aluminum nitride (AlN), indium nitride (InN), tungstenlanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide (In₂O₃),antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃).

In some embodiments, the system includes a first arc chamber liner thatis made from a tungsten-containing material, and a second arc chamberliner that is made from a non-tungsten-containing material such as onethat is made of graphite, carbide, or a ceramic, as described herein. Inother embodiments, the system includes a first arc chamber liner that ismade from a tungsten-containing material, and a second arc chamber linerthat is made from a mixture of tungsten-containing material and anon-tungsten-containing material. For example, the second arc chamberliner can be formed from a tungsten-containing material but that issurface graded or coated with graphite, carbide, or ceramic.

In examples, the second liner of the ion implantation system cancomprise, consist of, or consist essentially of graphite (C), boron (B),germanium (Ge), boron nitride (BN), boron oxide (B₂O₃), germanium oxide(GeO₂), silicon carbide (SiC), tungsten carbide (WC, W₂C), tungstenboride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungstengermanium (W₂Ge₃), calcium carbide (CaC₂), aluminum carbide (Al₄C₃),magnesium carbide (Mg₂C), aluminum fluoride (AlF₃), gallium fluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN), gallium nitride(GaN), aluminum nitride (AlN), indium nitride (InN), tungsten lanthanumoxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide (In₂O₃), antimonyoxide (Sb₂O₃) or aluminum oxide (Al₂O₃), or a combination thereof. Anexample consumable structure can comprise at least 50, 60, 70, 80, 90,or 95 percent by weight graphite (C), silicon carbide (SiC), elementalboron (B), boron carbide (B₄C, B₁₂C₃), aluminum carbide (Al₄C₃),magnesium carbide (Mg₂C). According to the present description, amaterial or structure that is said to “consist essentially of” a listedmaterial or combination of materials, is a material or structure thatcontains the listed material or combination of materials and not morethan an insubstantial amount of any other ingredients or materials;accordingly, a structure that consists essentially of graphite (C),elemental boron (B), silicon carbide (SiC), or a combination thereof,contains at least 97, 99, or 99.5 weight percent graphite (C), elementalboron (B), silicon carbide (SiC), or a combination thereof, and not morethan 3, 1, or 0.5 weight percent of any other materials.

In some embodiments, the arc chamber includes two or more a, including afirst liner made from tungsten carbide (WC, W₂C) and a second liner madefrom silicon carbide (SiC). In some embodiments, the arc chamberincludes a first liner made from tungsten carbide (WC, W₂C) and a secondliner made from graphite (C). In some embodiments, the arc chamberincludes a first liner made from tungsten carbide (WC, W₂C) and a secondliner made from boron carbide (B₄C, B₁₂C₃). In some embodiments, the arcchamber includes a first liner made from tungsten carbide (WC, W₂C) anda second liner made from calcium carbide (CaC₂). In some embodiments,the arc chamber includes a first liner made from tungsten carbide (WC,W₂C) and a second liner made from aluminum carbide (Al₄C₃). In someembodiments, the arc chamber includes a first liner made from tungstencarbide (WC, W₂C) and a second liner made from magnesium carbide (Mg₂C).

In some modes of fabrication, one or more non-tungsten materials areintegrated into the structural material of an arc chamber wall or an arcchamber liner. For example, an arc chamber wall or arc chamber liner canbe “surface graded” (e.g., “infused”) with any one or more of thematerials described herein, such as graphite (C), boron (B), germanium(Ge), boron nitride (BN), boron oxide (B₂O₃), germanium oxide (GeO₂),silicon carbide (SiC), tungsten carbide (WC, W₂C), tungsten boride (WB,W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungsten germanium (W₂Ge₃),calcium carbide (CaC₂), aluminum carbide (Al₄C₃), magnesium carbide(Mg₂C), aluminum fluoride (AlF₃), gallium fluoride(GaF₃), indiumfluoride (InF₃), boron nitride (BN), gallium nitride (GaN), aluminumnitride (AlN), indium nitride (InN), tungsten lanthanum oxide (WLa₂O₃),gallium oxide (Ga₂O₃), indium oxide (In₂O₃), antimony oxide (Sb₂O₃) oraluminum oxide (Al₂O₃), including any of the particular forms describedherein. Surface grading can be accomplished by applying a desirednon-tungsten material (graphite, carbide, etc.) to the metal surface ofan arc chamber wall or liner and then heating the surface to integratethe non-tungsten material into the metal of the arc chamber wall orliner. The non-tungsten material becomes present at high density at thesurface of the structure and can provide a protective barrier. Surfacegrading can be over all or a portion of the surface (interior) of thearc chamber wall or arc chamber liner.

In some embodiments the arc chamber wall or arc chamber liner is fullyor partially modified or made from a graphite-containing material, acarbide-containing material, or a ceramic, that is in particulate form.Exemplary forms of these materials can be PLS (10 micron graphite), DFP(5 micron graphite), DFP3-2 (densified graphite), SCF (hard graphite),SCF-PYC (hard 5 micron graphite with pyrocarbon coating), SCF-IF (hard 5micron graphite with pyrocarbon infiltration), ZEE (hard 1 microngraphite), ZEE-PYC (hard 1 micron graphite with pyrocarbon coating),ZEE-IF (hard 1 micron graphite with pyrocarbon infiltration), SUPERSiC,SUPERSiC-GS (graphite with SiC composite layer), of a combination of anytwo or more of these materials. Any of these materials can be used tomake the insertable liner, wherein any one or more of these materialsare used to form a non-graded liner, surface graded liner, or surfacecoated liner.

Alternatively, the arc chamber wall or liner can be non-graded butotherwise modified to associate the desired non-tungsten material withmaterial of the arc chamber wall or liner. For example, in another modeof modification, a desired non-tungsten material (graphite, carbide,etc.) is surface coated on all or a portion of the metal surface of thearc chamber wall or liner. In a surface coating the non-tungstenmaterial forms a coated layer on the metal surface, but is notnecessarily integrated into the metal. The coated layer can be formed byone of a variety of techniques such as coating the non-tungsten materialusing heat, coating using pressure, or by sputter coating. The coatedlayer can be of a desired thickness, such as a thickness in the range ofabout 1 nanometer to about 5 millimeters. Surface coating can be overall or a portion of the surface (interior) of the arc chamber innerwalls.

As noted herein, the different materials of the arc chamber can bedescribed in terms of a percentage of an area of the interior-plasmafacing surfaces of the arc chamber. A percentage of the area of theinterior-plasma facing surfaces of the arc chamber can include thesecond, different, arc chamber material. The second arc chamber materialcan be in the form of a liner, a coating, or a surface grading, on aportion of the inner surfaces. The interior facing surfaces of the arcchamber can include a first sidewall, a second sidewall, a cathodesidewall, an anti-cathode sidewall, a bottom, and a top of the arcchamber. All or a portion of any one or more of these interior-plasmafacing surfaces can include the second, different, arc chamber material.

In some embodiments, the arc chamber walls have a total interior-plasmafacing surface area and the system includes at least one arc chamberliners comprising the second arc chamber material (e.g., carbide,graphite, etc.), and the at least one arc chamber liners cover an amountof the total interior-plasma facing surface area of the walls in therange of about 1% to about 99%. More specifically, the at least one arcchamber liners covers an amount in the range of about 30% to about 70%of the total interior-plasma facing surface area. Even morespecifically, the at least one arc chamber liners covers an amount inthe range of about 40% to about 60% of the total interior-plasma facingsurface area.

In some embodiments, the system includes at least two arc chamberliners, with a first liner made from a first material such as tungsten,and a second liner made from a second material such as graphite, boride,or carbide as described herein, wherein the second arc chamber linercovers an amount of the total interior-plasma facing surface area of thewalls in the range of about 1% to about 99%, about 30% to about 70%, orabout 40% to about 60% of the total interior-plasma facing surface area.

In some embodiments, the arc chamber walls have a total interior-plasmafacing surface area and the system comprises at least a portion of theinterior facing walls that are coated or surface graded with the secondarc chamber material (e.g., carbide, graphite, etc.), wherein an amountin the range of about 1% to about 99% of the total interior-plasmafacing surface area is coated or surface graded with the second arcchamber material. More specifically, an amount in the range of about 1%to about 99% of the total interior-plasma facing surface area is coatedor surface graded with the second arc chamber material. Even morespecifically, an amount in the range of about 1% to about 99% of thetotal interior-plasma facing surface area is coated or surface gradedwith the second arc chamber material.

In the system of disclosure and as noted herein, the arc chamber caninclude facing surfaces that include interior facing surfaces of a firstsidewall, a second sidewall, a cathode sidewall, an anti-cathodesidewall, a bottom, and a top of the arc chamber. One or more arcchamber liner(s) can be configured to cover any part or all of any oneor more of these interior surfaces. In embodiments, the system comprisesone arc chamber liner including the second arc chamber material (e.g.,carbide, graphite, etc.) that is configured to cover all or a portion ofone of the first sidewall, a second sidewall, a cathode sidewall, ananti-cathode sidewall, a bottom, or a top of the arc chamber. Inembodiments, the system comprises two, three, four, five, or six arcchamber liners including the second arc chamber material (e.g., carbide,graphite, etc.) that are configured to cover all or a portion of two ofthe first sidewall, a second sidewall, a cathode sidewall, ananti-cathode sidewall, a bottom, and a top of the arc chamber.

In other embodiments, the system includes two or more arc chamberliners, each being formed from a different material. For example, afirst arc chamber liner can be formed from tungsten, and a second arcchamber liner can be formed from a non-tungsten material, such ascarbide, graphite, etc. The first arc chamber liner and the second arcchamber liner can be configured to cover any parts or all of two or moreof the interior facing surfaces of a first sidewall, a second sidewall,a cathode sidewall, an anti-cathode sidewall, a bottom, and a top of thearc chamber. In some embodiments the system includes a first arc chamberliner configured to cover all of one of the interior facing surfaces asdescribed herein, and a second arc chamber liner configured to cover allof one of the interior facing surfaces as described herein. In yet otherembodiments the system provides two or more of arc chamber liners madefrom a first material (e.g., tungsten) and one arc chamber liner madefrom a different material (e.g., carbide, graphite, etc.). In yet otherembodiments the system provides one arc chamber liners made from a firstmaterial (e.g., tungsten) and two or more arc chamber liners made from adifferent material (e.g., carbide, graphite, etc.). In yet otherembodiments the system provides two or more arc chamber liners made froma first material (e.g., tungsten) and two or more arc chamber linersmade from a different material (e.g., carbide, graphite, etc.).

In still other embodiments, the second arc chamber material can beprovided as a separate piece or target that is mounted in the arcchamber or received in a recess formed in the liner or the arc chamberwalls for this purpose. The separate piece may be of any suitable shapeor size such that it can be disposed in the arc chamber. In oneembodiment, the separate piece includes the second arc chamber materialand the arc chamber walls and/or liner includes the first arc chambermaterial, the first and second arc chamber materials being differentfrom one another. In embodiments, the separate piece is a consumablestructure and chemically reacts with the ionizable gas or gas mixture,or ions or neutral generated from the ionizable gas or gas mixture inarc chamber plasma, and produces desired species into plasma. In anembodiment, the separate piece is a sputter target capable of producingdesired species into plasma. The second material used to form theseparate piece can be any one of graphite (C), boron (B), germanium(Ge), boron nitride (BN), boron oxide (B₂O₃), germanium oxide (GeO₂),silicon carbide (SiC), tungsten carbide (WC, W₂C), tungsten boride (WB,W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃), tungsten germanium (W₂Ge₃),calcium carbide (CaC₂), aluminum carbide (Al₄C₃), magnesium carbide(Mg₂C), aluminum fluoride (AlF₃), gallium fluoride(GaF₃), indiumfluoride (InF₃), boron nitride (BN), gallium nitride (GaN), aluminumnitride (AlN), indium nitride (InN), tungsten lanthanum oxide (WLa₂O₃),gallium oxide (Ga₂O₃), indium oxide (In₂O₃), antimony oxide (Sb₂O₃) oraluminum oxide (Al₂O₃). In some cases, the selection of the secondmaterial used to form the separate piece or target can be selected basedon the gas or gas mixture to be ionized by the ion implantation system.Because the piece is separate, it may be removed and replaced with adifferent material depending on the desired ion implant application.Also, if consumable, once consumed, the separate piece can be replacedwith a new separate piece.

In use, a gas or gas mixture capable of generating ionic species can beflowed into the arc chamber containing the at least two different arcchamber materials at a predetermined flow rate. The gas or gas mixtureis an ionizable gas or gas mixture that includes one or more species tobe implanted in a substrate during an ion implantation process. Uponapplication of a predetermined power and voltage in the arc chamber,ionic species can be generated from the gas or gas mixture, with thespecies including one or more desired ionic species for implantationinto the substrate. Using optimized operating conditions of the system,the beam current of the desired ionic species is increased to a greaterextent than any of the other ionic species due to the presence of thesecond arc chamber material, relative to the beam currents of the ionicspecies generated without the second arc chamber material under the sameoperating conditions. Using this method, the ionic species with thegreatest beam current can be selected for implantation into thesubstrate. In some cases, a bias voltage can be applied to the arcchamber liner(s), portions of the arc chamber forming the arc chamberliner, or the separate piece disposed in the arc chamber.

Gases for ionization in combination with at least two different arcchamber materials include, but are not limited to silicon containinggases, boron containing gases, germanium containing gases, carboncontaining gases, phosphorus containing gases, arsenic containing gases,antimony containing gases, tungsten containing gases, nitrogencontaining gases, gallium containing gases, indium containing gases,aluminum containing gases, fluorine containing gases, tin containinggases, or hydrogen containing gases. In some embodiments, the gas can bean enriched gas isotopically enriched in one or more isotopes relativeto their natural abundance. Exemplary enriched gases include anisotopically enriched boron containing gas including with isotopicallyenriched boron in B-11 isotope and an isotopically enrichedgermanium-containing gas enriched in one or more germanium isotopes suchas Ge-72 isotope. The ionizable gas can be co-flowed or provided inmixture with at least one other gas. The at least one other gas caninclude a co-gas which contains the same species as the ionizable gas,and/or a diluent or carrier gas.

Examples of specific gases for ionization in in combination with atleast two different chamber materials include, but are not limited to,SiF₄, Si₂F₆, Si₂H₄, SiHF₃, SiH₂F₂, Si₂H₃F₃, Si₂H₅F, Si₂HF₅, BF₃, B₂F₄,B₂H₆, BHF, BHF₂, GeF₄, Ge₂F₆, GeH₄, GeHF₃, GeH₂F₂, GeH₃F, PF₃, PF₅, PH₃,PHF₂, PH₂F, PH₃F₂, P₂HF, AsHF₂, AsH₂F, AsH₃F₂, AsF₃, AsF₅, AsH₃, SbF₅,WF₆, NF₃, N₂F₄, NH₃, NHF₂, NH₂F, NHF, and N₂H₃F, CO, COF₂, CH₄, CF₄,C₂F₆ and gases having the following general formulaC_(n)H_(x)F_(2n+2−x), C_(n)H_(x)F_(2n−x), C_(n)H_(x)F_(2n−2−x), whereinn is an integer in the range of 1-3, and x is 0, 1, or 2. Examples ofenriched gases for ionization in in combination with at least twodifferent chamber materials include, but are not limited to,isotopically enriched BF₃ gas and isotopically enriched GeF₄ gas.

Referring now to the drawings, FIG. 1 is a schematic representation ofan ion implantation system 10, including an arc chamber 12 with a gasfeed line 14 for feeding an ion-generating gas (e.g., fluoride gas) tothe arc chamber for ionization thereof in the chamber. The arc chamber12 includes two or more arc chamber materials, at least one of thematerials or liners being formed from a non-tungsten material.

Referring now to the drawings, FIG. 1 is a schematic representation ofan ion implantation system 10, including an arc chamber 12 with a gasfeed line 14 for feeding an ion-forming gas, such as fluoride gas, tothe arc chamber for ionization thereof in the chamber. The arc chamber12 thus provides an ion source chamber that includes two or moredifferent arc chamber materials as disclosed herein. The use of the twodifferent arc chamber materials can provide benefits such as improvedbeam current, reduced source power, longer source life, lower gas flow,and reduced buildup of unwanted contaminants in the chamber, or anycombination thereof.

FIG. 2 is a cross section of the FIG. 1 ion implantation system 10schematically showing the generation of a plasma 16 in the arc chamber12 of such system. The gas (e.g., fluoride gas) is flowed in thedirection indicated by arrow A into the gas feed line 14, havingmonitoring thermocouples TC1 and TC2 secured thereto in monitoringrelationship to determine the quality of the thermal state of the feedline and gas entering the arc chamber, as may be desirable in connectionwith the use of a thermal management system for the ion implantationsystem.

FIG. 3 is a perspective view, in cross-section, of the ion sourceassembly comprising the ion source apparatus 70 and an optional heatsink apparatus 50 for thermal management of the system. Thiscross-sectional view shows the gas feed line 72 connecting to gas flowpassage 84 in the gas feed plug and to the gas flow passage 86 in thegas bushing associated with the ion source.

The ion source apparatus shown in FIG. 3 includes a base liner 80 thatis made from a first arc chamber material. The base liner 80 can includean opening 82 therein. The ion source apparatus shown in FIG. 3 alsoincludes a side liner 90 that is made from a second arc chamber materialdifferent than the first arc chamber material. In one embodiment, thefirst arc chamber material is a tungsten containing material and thesecond arc chamber material is a non-tungsten containing material. Thefirst and second arc chamber materials can be selected from thematerials previously disclosed herein.

FIG. 4 is a schematic representation of an ion implant process system300 including a storage and dispensing vessel 302 holding a reactant gaswhich is supplied for in situ reaction with an ion-generating gas in theion source chamber to generate an ionic species for ion implantation ofa substrate 328 in the illustrated ion implant chamber 301. The storageand dispensing vessel 302 comprises a vessel wall 304 enclosing aninterior volume holding the gas.

The vessel may be a gas cylinder of conventional type, with an interiorvolume arranged to hold only gas, or alternatively, the vessel maycontain a sorbent material having sorptive affinity for the reactantgas, and from which the co-reactant source gas is desorbable fordischarge from the vessel under dispensing conditions.

The storage and dispensing vessel 302 includes a valve head 308 coupledin gas flow communication with a discharge line 312. A pressure sensor310 is disposed in the line 312, together with a mass flow controller314. Other monitoring and sensing components may be coupled with theline, and interfaced with control means such as actuators, feedback andcomputer control systems, cycle timers, etc.

The ion implant chamber 301 contains an ionizer 316 receiving thedispensed ion-generating gas (e.g., fluoride gas) from line 312 thatunder the ionization conditions in the ionizer chamber produce an ionbeam 305. The ion beam 305 passes through the mass analyzer unit 322which selects the ions needed and rejects the non-selected ions.

The selected ions pass through the acceleration electrode array 324 andthen the deflection electrodes 326. The resultingly focused ion beam isimpinged on the substrate element 328 disposed on the rotatable holder330 mounted in turn on spindle 332, to form a doped (fluoride-doped)substrate as the ion implantation product.

The respective sections of the ion implant chamber 301 are exhaustedthrough lines 318, 340 and 344 by means of pumps 320, 342 and 346,respectively.

FIG. 5 is a top-down view of an interior of an ion source chamber 100that includes arc chamber walls 102 a, 102 b, 102 c, and 102 d. In thechamber at one end is cathode 104, and at the other end anti-cathode106. The arc chamber walls are covered with arc chamber liners 110, 112,114, and 116, on the side walls, and also arc chamber liner 118 on thebottom side. On the bottom wall there is also a gas input opening 108.In embodiments, one, two, three, four, or five of arc chamber liners110, 112, 114, 116 and/or 118 can be made from different materialsselected from a tungsten material or a non-tungsten material, such asgraphite (C), boron (B), germanium (Ge), boron nitride (BN), boron oxide(B₂O₃), germanium oxide (GeO₂), silicon carbide (SiC), tungsten carbide(WC, W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C,B₁₂C₃), tungsten germanium (W₂Ge₃), calcium carbide (CaC₂), aluminumcarbide (Al₄C₃), magnesium carbide (Mg₂C), aluminum fluoride (AlF₃),gallium fluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN),gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN),tungsten lanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide(In₂O₃), antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃). Inembodiments, one or more of the non-tungsten liner(s) is made fromboride, carbide, or a graphite material.

FIG. 6 is a top-down view of an interior of another ion source chamber200 that includes arc chamber walls 202 a, 202 b, 202 c, and 202 d. Inthe chamber at one end is cathode 204, and at the other end anti-cathode106. The arc chamber walls are covered with arc chamber liners 210, 212,214, and 216, on the side walls, and also arc chamber liners 218, 220,and 222 on the bottom side. On the bottom wall there is also a gas inputopening 208. In embodiments, one, two, three, four, five, or six of arcchamber liners 210, 212, 214, 216, 218, 220 and/or 222 can be made fromdifferent materials selected from a tungsten material or non-tungstenmaterials such as graphite (C), boron (B), germanium (Ge), boron nitride(BN), boron oxide (B₂O₃), germanium oxide (GeO₂), silicon carbide (SiC),tungsten carbide (WC, W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boroncarbide (B₄C, B₁₂C₃), tungsten germanium (W₂Ge₃), calcium carbide(CaC₂), aluminum carbide (Al₄C₃), magnesium carbide (Mg₂C), aluminumfluoride (AlF₃), gallium fluoride(GaF₃), indium fluoride (InF₃), boronnitride (BN), gallium nitride (GaN), aluminum nitride (AlN), indiumnitride (InN), tungsten lanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃),indium oxide (In₂O₃), antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃).In embodiments, one or more of the two different non-tungsten liner(s)is made from carbide, and one or more of the other of the differentnon-tungsten liner(s) is of the or a graphite material.

FIG. 7A is a top-down view of an interior of an ion source chamber 400.Ion source chamber 400 includes arc chamber walls 402 a, 402 b, 402 c,and 402 d. In the chamber at one end is cathode 404, and at the otherend anti-cathode 406. The arc chamber walls 402 d and 402 c are coveredwith arc chamber liners 414, and 416, respectively. Arc chamber liner418 is a nonplanar one-piece liner that covers the side walls 402 a and402 b, and the bottom side of the chamber. On the bottom there are alsogas input openings 408 a and 408 b. In embodiments, one, two, or allthree of arc chamber liners 414, 416 and/or 418 can be made from atungsten material or a non-tungsten material, such as graphite (C),boron (B), germanium (Ge), boron nitride (BN), boron oxide (B₂O₃),germanium oxide (GeO₂), silicon carbide (SiC), tungsten carbide (WC,W₂C), tungsten boride (WB, W₂B, WB₂, WB₄), boron carbide (B₄C, B₁₂C₃),tungsten germanium (W₂Ge₃), calcium carbide (CaC₂), aluminum carbide(Al₄C₃), magnesium carbide (Mg₂C), aluminum fluoride (AlF₃), galliumfluoride(GaF₃), indium fluoride (InF₃), boron nitride (BN), galliumnitride (GaN), aluminum nitride (AlN), indium nitride (InN), tungstenlanthanum oxide (WLa₂O₃), gallium oxide (Ga₂O₃), indium oxide (In₂O₃),antimony oxide (Sb₂O₃) or aluminum oxide (Al₂O₃). In embodiments, one ormore of the non-tungsten liner(s) is made from boron, boride, carbide ora graphite material.

FIG. 7B is perspective cross sectional view of the ion source chamber400 of FIG. 7A. Arc chamber walls 402 a, 402 b, and 402 c are shown. Theion source chamber 400 also includes top cover 420. Arc chamber liner418, which has a “U-shape” as seen from the cross section, is aone-piece liner that covers the interior facing surfaces of side walls402 a and 402 b, and also the bottom 422. While a non-planar U-shapedarc chamber liner is shown in FIGS. 7A and 7B, the system can includeother one-piece arc chamber liners of other shapes (e.g., “L-shaped”,“V-shaped,” etc.) that are able to covering two or more adjacentsurfaces of the interior of the arc chamber, such as two, three, four,or five surfaces selected from the first sidewall, the second sidewall,the cathode sidewall, the anti-cathode sidewall, the bottom, and thetop.

The system and method of the disclosure can include or use a gas sourcethat provides a gas that is ionizable to one or more desired ionicspecies. In some embodiments, the gas source includes one or moreionizable silicon containing gases including, but not limited to, SiF₄,Si₂F₆, Si₂H₆, SiHF₃, SiH₂F₂, SiH₃F, Si₂H₃F₃, Si₂H₅F, and Si₂HF₅. In someembodiments, the gas source includes one or more ionizable boroncontaining gases including, but not limited to, BF₃, B₂F₄, B₂H₆, BHF,and BHF₂. In some embodiments, the gas source includes one or moreionizable germanium containing gases including, but not limited to,GeF₄, Ge₂F₆, GeH₄, Ge₂H₆, GeHF₃, GeH₂F₂, and GeH₃F. In some embodiments,the gas source includes one or more ionizable phosphorus containinggases including but not limited to PF₃, PF₅, PH₃, PHF₂, PH₂F, PHF₃ andP₂H₄. In some embodiments, the gas source includes one or more ionizablearsenic containing gases including, but not limited to, AsHF₂, AsH₂F,AsHF₂, AsF₃, AsF₅, and AsH₃. In some embodiments, the gas sourceincludes one or more ionizable antimony containing gases including SbH₃and SbF₅. In other embodiments, the gas source can include WF₆. In someembodiments, the gas source can include one or more ionizable nitrogencontaining gases including, but not limited to NF₃, N₂F₄, NH₃, NHF₂,NH₂F, and N₂H₃F. In some embodiments, the gas source can include one ormore ionizable carbon containing gases including, but not limited to,CO, COF₂, CH₄, CF₄, C₂F₆ and gases having the following general formulaC_(n)H_(x)F_(2n+2−x), C_(n)H_(x)F_(2n−x), C_(n)H_(x)F_(2n−2−x), whereinn is an integer in the range of 1-3, and x is 0, 1, or 2. In still yetother embodiments, the gas source includes one or more ionizablefluorine containing gases, such as disclosed herein, capable ofgenerating a C⁺ ion, a B⁺ ion, a N⁺ ion, a r ion, a Si⁺ ion, an Ge⁺ ion,a P⁺ ion, an As⁺ ion, a Ga⁺ ion, a Sb⁺ ion, a In⁺ ion, a Al⁺ ion specieswhen ionized. In some embodiments, the gas source includes one or moreionizable inert gases selected from the group consisting of He, Ne, Ar,Kr, Xe and N₂. Additionally, if two or more different ionizable gasesare used, these may be flowed into the implantation chamberindependently, or can be flowed as a mixture into the chamber.

In preferred embodiments, a gas source for the ion implantation of aboron species can include: BF₃ gas, B₂F₄ gas, or B₂H₆ gas; or a gasmixture containing a first boron containing gas including BF₃ gas, B₂F₄gas, or B₂H₆ gas, a second boron containing gas including BF₃ gas, B₂F₄gas, or B₂H₆ and/or a diluent gas such as hydrogen gas, a noble gas (He,NE, Ar, Kr, Xe) or a mixture of hydrogen gas with noble gas (e.g.Xe/H₂). The gas source, as described herein, is delivered to an arcchamber including a first arc chamber material including tungsten and asecond arc chamber material including a boron containing material suchas elemental boron, boron carbide, boron nitride, boron oxide, tungstenboride. The first and second arc chamber materials can be a first linermaterial and a second liner material, respectively. In one embodiment,the first liner material includes tungsten and the second liner includesboron nitride. In another embodiment, the first liner material includestungsten and the second liner material includes boron carbide. In yetanother embodiment, the first liner material includes tungsten and thesecond liner material includes tungsten boride. In yet anotherembodiment the first liner material includes tungsten and a second linermaterial includes boron oxide. In still yet another embodiment, thefirst liner material includes tungsten and the second liner materialincludes elemental boron.

In one preferred embodiment, an ionizable gas source including BF₃ canbe flowed into an arc chamber where a first arc chamber material istungsten and a second arc chamber material is one of elemental boron,boron oxide, boron nitride, boron carbide or tungsten boride. The firstarc chamber material can form all or a portion of a first liner and thesecond arc chamber material can form all or a portion of a second liner.In some cases, the ionizable gas source is a gas mixture including BF₃and hydrogen. The BF₃ can be isotopically enriched, but this is notrequired.

Without wishing to be bound to any theory, it is believed that anionizable gas generates reactive ionic or neutral species such as BF₃+,BF+, F+, BF₂, BF, F that can chemically react with the second linermaterial and preferentially volatilize boron species from the secondliner material for further ionization in arc chamber plasma. Thevolatilized boron species increase the concentration of boron-containingspecies in plasma and consecutively increases beam current of desiredboron-containing ions such as B+ or BF₂+. Further, a gas mixture mayinclude one or more gases that can facilitate volatilization of boronspecies from the second liner through chemical reaction or sputtering.Examples of such gases are F₂, NF₃, N₂F₄, XeF₂ for enhancing chemicalreaction or noble gases for enhancing sputtering. In addition, a gasmixture may include one or more gases that can suppress unwanted effectsthat reduce volatilization of desired boron species or enhancevolatilization of unwanted species such tungsten fluorides. An exampleof such a gas includes H₂ or other hydrogen containing gas that can bindfree fluorine that can case excessive volatilization of tungsten.

In another embodiment, an ionizable gas including CF₄ can be flowed intoan arc chamber where a first arc chamber material is graphite and asecond arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including CF₄ and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is graphite and asecond arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including GeF₄ and hydrogen. Additionally, in somecases, the GeF₄ can be isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is graphite and asecond arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including BF₃ and hydrogen. Additionally, in somecases, the BF₃ can be isotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is graphite and asecond arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including SiF₄ and hydrogen.

In another embodiment, an ionizable gas including CF₄ can be flowed intoan arc chamber where a first arc chamber material is silicon carbide anda second arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including CF₄ and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is siliconcarbide and a second arc chamber material is tungsten. In some cases,the ionizable gas is a gas mixture including GeF₄ and hydrogen.Additionally, in some cases, the GeF₄ can be isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is silicon carbide anda second arc chamber material is tungsten. In some cases, the ionizablegas is a gas mixture including BF₃ and hydrogen. Additionally, in somecases, the BF₃ can be isotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is siliconcarbide and a second arc chamber material is tungsten. In some cases,the ionizable gas is a gas mixture including SiF₄ and hydrogen. Inanother embodiment, an ionizable gas including CF₄ can be flowed into anarc chamber where a first arc chamber material is tungsten, a second arcchamber material is graphite and a third arc chamber material is siliconcarbide. In some cases, the ionizable gas is a gas mixture including CF₄and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is tungsten, asecond arc chamber material is graphite and a third arc chamber materialis silicon carbide. In some cases, the ionizable gas is a gas mixtureincluding GeF₄ and hydrogen. Additionally, in some cases, the GeF₄ canbe isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is tungsten, a secondarc chamber material is graphite and a third arc chamber material issilicon carbide. In some cases, the ionizable gas is a gas mixtureincluding BF₃ and hydrogen. Additionally, in some cases, the BF₃ can beisotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is tungsten, asecond arc chamber material is graphite and a third arc chamber materialis silicon carbide. In some cases, the ionizable gas is a gas mixtureincluding SiF₄ and hydrogen.

In another embodiment, an ionizable gas including CF₄ can be flowed intoan arc chamber where a first arc chamber material is tungsten, a secondarc chamber material is graphite and a third arc chamber material issilicon carbide. In some cases, the ionizable gas is a gas mixtureincluding CF₄ and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is tungsten, asecond arc chamber material is graphite and a third arc chamber materialis silicon carbide. In some cases, the ionizable gas is a gas mixtureincluding GeF₄ and hydrogen. Additionally, in some cases, the GeF₄ canbe isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is tungsten, a secondarc chamber material is graphite and a third arc chamber material issilicon carbide. In some cases, the ionizable gas is a gas mixtureincluding BF₃ and hydrogen. Additionally, in some cases, the BF₃ can beisotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is tungsten, asecond arc chamber material is graphite and a third arc chamber materialis silicon carbide. In some cases, the ionizable gas is a gas mixtureincluding SiF₄ and hydrogen.

In another embodiment, an ionizable gas including CF₄ can be flowed intoan arc chamber where a first arc chamber material is tungsten carbide, asecond arc chamber material is tungsten, and a third arc chambermaterial includes graphite or silicon carbide. In some cases, theionizable gas is a gas mixture including CF₄ and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is tungstencarbide, a second arc chamber material is tungsten, and a third arcchamber material includes graphite or silicon carbide. In some cases,the ionizable gas is a gas mixture including GeF₄ and hydrogen.Additionally, in some cases, the GeF₄ can be isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is tungsten carbide, asecond arc chamber material is tungsten, and a third arc chambermaterial includes graphite or silicon carbide. In some cases, theionizable gas is a gas mixture including BF₃ and hydrogen. Additionally,in some cases, the BF₃ can be isotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is tungstencarbide, a second arc chamber material is tungsten, and a third arcchamber material includes graphite or silicon carbide. In some cases,the ionizable gas is a gas mixture including SiF₄ and hydrogen.

In another embodiment, an ionizable gas including CF₄ can be flowed intoan arc chamber where a first arc chamber material is tungsten boride, asecond arc chamber material is tungsten, and a third arc chambermaterial includes graphite or silicon carbide. In some cases, theionizable gas is a gas mixture including CF₄ and hydrogen.

In another embodiment, an ionizable gas including GeF₄ can be flowedinto an arc chamber where a first arc chamber material is tungstenboride, a second arc chamber material is tungsten, and a third arcchamber material includes graphite or silicon carbide. In some cases,the ionizable gas is a gas mixture including GeF₄ and hydrogen.Additionally, in some cases, the GeF₄ can be isotopically enriched.

In another embodiment, an ionizable gas including BF₃ can be flowed intoan arc chamber where a first arc chamber material is tungsten boride, asecond arc chamber material is tungsten, and a third arc chambermaterial includes graphite or silicon carbide. In some cases, theionizable gas is a gas mixture including BF₃ and hydrogen. Additionally,in some cases, the BF₃ can be isotopically enriched.

In another embodiment, an ionizable gas including SiF₄ can be flowedinto an arc chamber where a first arc chamber material is tungstenboride, a second arc chamber material is tungsten, and a third arcchamber material includes graphite or silicon carbide. In some cases,the ionizable gas is a gas mixture including SiF₄ and hydrogen.

In the presence of the arc chamber that uses two or more differentmaterials such as described herein there are benefits for implantationof ionic species at predetermined gas flow rates. For example, using anarc chamber with two different materials, a substantially higher beamcurrent for certain ionic species can be achieved at gas flow rates thatotherwise provide lower beam currents for those ionic species whenmixtures of different arc chamber materials are not used. Since a higherionic species beam current can be achieved using a mixture of arcchamber materials, this allows the user to reduce the flow rate of theionizable gas in certain modes of practice, and this can in turn providevarious processing benefits, such as reduction of overall reagentconsumption, less equipment maintenance, and increased lifetime ofimplantation equipment.

Also, the use of the mixture of different arc chamber materials canprovide higher beam currents for certain ionic species generated uponionization of the ionic species-generating gas. This can be beneficialfor the implantation of certain ionic species that have higher beamcurrents, while minimizing the implantation of other ionic species thathave lower beam currents, relative to the beam currents observed forthose species when mixtures of different arc chamber materials are notused. Therefore, the disclosure provides methods for selectivelydepositing desired ions into a substrate which can ultimately improvesproduct properties and performance.

Even further, the use of the mixture of different arc chamber materialscan provide lower amounts of undesirable ionic species that aregenerated during the deposition process. If the arc implantation chamberis formed using, in part, a tungsten-containing material, ionization ofthe gas source can cause generation of ionic species such as W⁺⁺, WF_(x)⁺⁺, W⁺, and WF_(x) ⁺ (x=1, 2, 3, 4, 5, 6). The use of a non-tungstenmaterial in the chamber, such as a graphite or carbide liner, candecrease the amounts of W⁺⁺, WF_(x) ⁺⁺, W⁺, and WF_(x) ⁺ (x=1, 2, 3, 4,5, 6) ionic species generated during the deposition process as comparedto a system that does not use a non-tungsten liner. Since these tungstenionic species can unwantedly be deposited in the implantation chamberthe reduction can improve the deposition process, decrease maintenanceof the implantation equipment, and increase overall life the equipment.

Operation of the system for ion implantation can be described in termsof the flow of the ion-generating gas into the chamber. During theprocess, the ion-generating gas is flowed into the implantation chamberat a desired flow rate and manner. The rate of flow of theion-generating gas can be maintained at a constant flow rate, oroptionally fluctuated during the deposition process. In some modes ofpractice, the flow of the ion-generating gas (e.g., fluoride gas) isflowed into the chamber at a rate not greater than 10 sccm, and inembodiments, ion-generating gas is flowed at a rate in the range of 0.1sccm to 6 sccm, or in the range of 0.3 sccm to 4 sccm.

Operation of the system for ion implantation can be described in termsof arc power and arc voltage. In some modes of practice, the system isoperated to provide an arc power in the range of about 5 W to about 2000W, or in some modes of practice an arc power is in the range of about 90W to about 1500 W. In order to achieve an arc power in one of theseranges, the system can be operated so arc power is generated at an arcvoltage in the range of about 20 V to about 200 V, or more specificallyis in the range of about 30 V to about 150 V, or in the range of about40 V to about 130 V.

Operation of the system for ion implantation can also be described interms of the flow rate of the gas source containing the ionizablecompound into the ion implantation chamber. In some embodiments,ionizable gas is flowed into the chamber at a rate not greater than 10sccm, and in embodiments, the fluoride compound is flowed at a rate inthe range of 0.1 sccm to 6 sccm.

If more than one gas is flowed to the chamber the gases can be flowedindividually. Alternatively, the gases can be flowed in mixture. Forexample, any two or more of the fluoride, hydrogen-containing,oxygen-containing and/or inert gases can be pre-mixture in gas cylinderpackage. In yet other embodiments, two or more gases are in mixture andthen another gas is individually flowed to the chamber.

EXAMPLES Example 1

A fluoride gas, CF₄, was flowed into an ionization chamber having atungsten liner and an ionization chamber having graphite and tungstenliners. The system was operated at an arc voltage of 110V and sourcebeam of 30 mA. F+ ion beam current was measured at various gas CF₄ flowrates, and compared to the F+ ion beam current in ionization chambershaving either a graphite liner, or a tungsten liner. At each flow ratetested, the system with the graphite and tungsten liners provided higherF⁺ beam currents as compared to the system with the tungsten liner, andsimilar or higher F⁺ beam currents as compared to the system with thegraphite liner. Results are shown in FIG. 8.

Example 2

The beam spectrums of various ionized species resulting from theprocesses described in Example 1 were determined. Results show that fromthe beam spectrum generated from ionized species of CF₄, a higher F⁺ ionbeam was observed when graphite and tungsten liners were used overeither a graphite liner, or a tungsten liner. However, the other speciesderived from CF₄ (C⁺, CF⁺, CF₂ ⁺, and CF₃ ⁺) had beam currents that werehigher when a graphite liner was used as the sole liner, as opposed tographite and tungsten liners used together, or a tungsten liner used byitself. Therefore, use of the graphite and tungsten liners togetherallows a selective improvement for F⁺ ion beam generation, which in turnimproves F⁻ implantation while minimizing implantation ofcarbon-containing ionic species. Further, a lower W⁺ and WF_(x) ⁺ beamswere observed when graphite and tungsten liners used, as compared totungsten liners used alone. See FIG. 9.

Having thus described several illustrative embodiments of the presentdisclosure, those of skill in the art will readily appreciate that yetother embodiments may be made and used within the scope of the claimshereto attached.

What is claimed is:
 1. An ion implantation system for implanting one ormore ionic species into a substrate, the system comprising: a gas sourcecomprising an ionizable gas or gas mixture containing at least oneionizable gas; and an arc chamber comprising at least a first arcchamber material and a second arc chamber material, wherein the firstand second arc chamber materials are different, wherein the arc chambercomprises arc chamber walls having interior-plasma facing surfaces andat least one of one or more arc chamber liners, a sputtering targetdisposed in the arc chamber, or a combination thereof, wherein the firstand second arc chamber materials are present in the arc chamber walls,in the one or more arc chamber liners disposed in the arc chamber, atarget disposed in the arc chamber, or a combination thereof.
 2. Thesystem of claim 1, wherein the arc chamber walls comprise the first arcchamber material, the first arc chamber material comprising tungsten,and wherein the second arc chamber material includes any one of boron,boron nitride, boron oxide, tungsten boride, or boron carbide.
 3. Thesystem of claim 2, wherein the second arc chamber material is coatedonto or surface graded into, a portion of or all of the arc chamberwalls.
 4. The system of claim 1, including a first liner including thefirst arc chamber material and a second liner including a second arcchamber material, wherein the first arc chamber material is tungsten andthe second arc chamber material is any one of one of boron, boronnitride, boron oxide, tungsten boride, or boron carbide.
 5. The systemof claim 1, wherein the gas source includes BF₃ gas and hydrogen.
 6. Thesystem of claim 1, wherein the gas source includes a first boroncontaining gas including BF₃, and a second boron containing gasincluding B₂F₄ gas or B₂H₆ gas.
 7. The system of claim 6, wherein thegas source further comprises a diluent gas, wherein the diluent gas canbe any one of hydrogen, krypton, neon, helium, argon, xenon, or axenon/hydrogen gas mixture.
 8. The system of claim 6, wherein the gassource further comprises one of hydrogen gas or a xenon/hydrogen gasmixture.
 9. The system of claim 1, wherein the gas source includes oneor more ionizable fluoride containing gases.
 10. The system of claim 9,the arc chamber walls comprise tungsten and the second arc chambermaterial forms at least a portion of an arc chamber liner and includesgraphite or a carbide containing compound.
 11. The system of claim 1,comprising a target disposed in the arc chamber, the arc chambercomprising a first arc chamber material and the target comprising thesecond arc chamber material.
 12. The system of claim 11, wherein thetarget reacts with or is sputtered by at least one of the ionizablegases or its ionic or neutral fragments.
 13. The system of claim 1,wherein the gas source and/or at least the first or second arc chambermaterial comprises an isotopically enriched material.
 14. The system ofclaim 13, wherein the gas source includes an ionizable gas includingisotopically enriched boron or isotopically enriched germanium.
 15. Thesystem of claim 13, wherein at least one of the first or second arcchamber materials is an isotopically enriched material.
 16. A method forimplanting one or more ion species into a substrate using the ionimplantation of claim 1, the method comprising: selecting at least oneof the first arc chamber material and the second arc chamber materialbased on the gas source; flowing the gas source into the arc chamber ata predetermined flow rate; generating ionic species from the gas sourceat a predetermined arc power and source magnet field, wherein the ionicspecies comprise a desired ionic species for substrate implantation;operating the system to implant the one or more ion species into thesubstrate. wherein the flow rate, arc power and source magnet field arechosen to provide a beam current for the desired ionic species that isincreased to a greater extent than any of the other ionic species whenthe second arc chamber material is used, relative to the beam currentsof the ionic species without the second arc chamber under the sameoptimal operating conditions.
 17. The method of claim 16, wherein thegas source includes an ionizable boron containing gas, the arc chamberwalls comprise the first arc chamber material, the first arc chambermaterial comprising tungsten, and wherein the second arc chambermaterial includes any one of boron, boron nitride, boron oxide, tungstenboride, or boron carbide.
 18. The method of claim 16, further comprisingdisposing a removable target comprising the second arc chamber materialin the arc chamber.
 19. The method of claim 16, wherein the ionizablegas source is a ionizable fluoride containing gas source whereinfluoride ionic species are generated from the fluoride gases, thefluoride ionic species comprise a desired fluoride ionic species forsubstrate implantation; and wherein the flow rate, arc power and sourcemagnet field are chosen to provide a beam current for the desiredfluoride ionic species that is increased to a greater extent than any ofthe other fluoride ionic species when the second arc chamber liner isused, relative to the beam currents of the fluoride ionic specieswithout the second arc chamber liner under the same optimal operatingconditions.
 20. The method of claim 16, wherein the first arc chambermaterial includes tungsten and the second arc chamber material includesgraphite or a carbide containing compound.